1. Field of the Invention
This invention relates to an apparatus with Sheet Curl Correction for storing one or more recorded sheets discharged from an image forming device such as a copying machine, and more particularly to a sheet storage apparatus having a mechanism capable of rationally operating a plurality of bin trays vertically juxtaposed to form accommodating spaces therebetween and widening the sheet accommodating space into which the recorded sheet fed from the image forming device is introduced.
2. Description of the Prior Art
The so-called "sorter" has been used for sorting recorded sheets discharged consecutively from an image forming device such as a copying machine, printer and facsimile into a sheaf or sheaves of sheets. Also, there have been a sheet post-processing apparatus and a finishing apparatus having functions of not only sorting the recorded sheets from the image forming device, but also stapling or punching the sorted sheets on demand. Every sheet handling apparatus of this kind is provided with a plurality of bin trays for receiving the recorded sheets fed from the image forming device one by one to make more than one sheaf of recorded sheets.
The closer the bin trays get to the adjacent bin trays, the larger the number of the bin trays becomes in a limited extent. That is, the capacity of storing the recorded sheets can be increased with narrowing the distance between the adjacent bin trays. However, as a sheet accommodating space defined between the vertically adjacent bin trays is narrowed by bringing the bin trays close to the adjacent one, it becomes difficult to introduce the recorded sheets from the image forming device into the sheet accommodating space and take out the finished sheaves of recorded sheets from the sheet accommodating space, and furthermore, the number of sheets which are permitted to be stacked on the respective bin trays is restricted.
For the purpose of mitigating the drawbacks described above, there have been so far proposed various mechanisms for widening a sheet accommodating space formed between the bin tray for stacking the recorded sheet and the overhead bin tray placed immediately thereabove at the time of introducing the recorded sheet from the image forming device thereinto. For instance, U.S. Pat. Nos. 4,986,520 and 4,621,803 are adduced.
A sorter described in U.S. Pat. No. 4,986,520 comprises a bin slider containing a plurality of multistage bins, which moves vertically to place the specified one of the bins at a sheet intake portion through which the sheet is admitted into a sheet accommodating space defined on the specified bin. In this known sorter, the sheet accommodating space for receiving the sheet is widened by using short lead cams. The conventional sorter serves to widen only the sheet accommodating space for receiving the sheet, but it is disadvantageous in that the bin slider containing the bins as noted above is complicated in structure and large in size, and it is difficult to actuate the lead cams synchronously with the bin slider.
Another sorter described in U.S. Pat. No. 4,621,803 is provided with bin shifting means composed of a pair of lead cam shafts for widening only a sheet accommodating space formed between adjacent bins at a sheet intake position. However, the bins in this conventional sorter are immovably held at their ends by support plates, and thus, render taking-out of the sheaves of sheets from the sheet accommodating spaces difficult because it is impossible to widen sheet outlet openings formed at the terminal ends of the bins. If the sheet outlet openings are made larger to facilitate the taking-out of the sheets from the accommodating spaces, the sorter is increased in size.
Furthermore, neither of the conventional sorters can cope with unexpected accident possibly resulting from the peculiar properties of the sheet to be handled or various conditions in which the sorter is operated. To be more specific, for example, in a typical image forming device such as a copying machine, a copying paper sheet is by and large curled or wraped as the result of being heated to fix a toner image with heat. Consequently, the conventional sorters are susceptible to sheet feeding troubles such as interference of the curled or wraped sheets, resulting in jamming or misalignment of the sheets stacked on the bin, but could not prevent such troubles. Moreover, since the conditions in which the sheet should be introduced from the image forming device into the sorter are affected by the thickness and properties of the sheet to be handled or other possible causes, they cannot be nonambiguously determined.
In a different sorter described in Japanese Patent Application Public Disclosure HEI 8-48458, in a case where a concavely curled sheet with its middle portion curved downward is fed from an image forming device, a sheet stacking bin holding the curled sheet thereon is moved upward so as to press the curled sheet against the lower surface of an overhead bin immediately above the sheet stacking bin in expectation of straightening the curled sheet. The sheet fed from the image forming device is, however, not always curled concavely, and there are times when it is curled convexly according to circumstances. Therefore, even though the sheet curled concavely or convexly is intended to be cured in the same manner of moving the sheet stacking bin upward, the curled sheet cannot necessarily be cured desirably.
Besides, there is a case where the sheet sent from the image forming device is not successfully released from intake rollers mounted at a sheet intake portion of the sorter, consequently causing the sheets stacked on the bin to be inconveniently disordered or jammed. The conventional sorters as noted above are not free from nor can remedy such disadvantages.
Incidentally, it is desired for the sheet sorting apparatus of this kind to align and compress the recorded sheets given from the image forming device and stacked on a stacking bin tray pertinently according to two processing modes, i.e. a non-sorting mode in which one sheaf of sheets is obtained without sorting, and a sorting mode in which two or more sheaves of sheets are obtained by sorting.
Additionally, when the sheaves of sheets are taken out from the sorting apparatus, it is required to make the sheet accommodating spaces wider than during the sheet being sent thereinto so as to take out the sheaves of sheets with ease. As a matter of course, simplicity in structure and easiness in handling are indispensable to the sorting apparatus of this kind.